This invention relates to leak detection methods and systems, and more particularly, to automotive fuel leak detection using a pressure switch and a temperature differential.
In a vapor handling system for a vehicle, fuel vapor that escapes from a fuel tank is stored in a canister. If there is a leak in the fuel tank, the canister, or any other component of the vapor handling system, fuel vapor could exit through the leak to escape into the atmosphere.
Vapor leakage may be detected through evaporative monitoring. Small leaks and large leaks may be detected by using a temperature and pressure in the vapor handling system and a processor. In detecting these leaks, it may be desirable to have low electrical consumption, a low cost to performance ratio, easy implementation and installation, and components independent of the processor.
The present invention provides a method of leak detection in a closed vapor handling system of an automotive vehicle. This method includes providing a vacuum detection component having a microcontroller operatively coupled to actuators and sensors, receiving at least one sensor signal from the sensors to the vacuum detection component, processing the at least one sensor signal in the microcontroller, sending output to an engine management system based on the at least one processed sensor signal, processing the output in the engine management system operatively coupled to a control valve, transmitting input from the engine management system to the vacuum detection component based on the processed output, and sending actuator signals from the microcontroller to the actuators.
The present invention also provides another method of leak detection in a closed vapor handling system of an automotive vehicle. This method includes providing a vacuum detection component having a microcontroller operatively coupled to a pressure switch, a temperature sensor, and a shut off valve, the vacuum detection component communicating with a power source and providing a communication interface, receiving a pressure signal and a temperature signal from the pressure switch and temperature sensor, respectively, by the microcontroller, processing the pressure signal and the temperature signal in the microcontroller, determining a diagnostic result in the microcontroller based on the signals, sending the diagnostic result to an engine management system, processing the diagnostic result in the engine management system, transmitting a diagnosis request, a reset diagnosis, purge status, and engine status from the engine management system to the microcontroller, and sending an operation request from the engine management system to the shut off valve. The diagnostic result includes whether a leak condition exits, whether a tank cap is missing and whether a component diagnoses fails. The engine management system is operatively coupled to a control valve, and the engine management system provides a communication interface and detects an onboard diagnostic error.
The present invention also provides an automotive evaporative leak detection system. This system includes a vacuum detection component having a microcontroller operatively coupled to actuators and sensors, which the microcontroller sends and receives, respectively, signals therefrom and a processor communicating with the microcontroller. The microcontroller processes the signals and sends output based on the processed signals to the processor. The processor processes the output and transmits input to the microcontroller based on the processed output.
The present invention further provides another automotive evaporative leak detection system. This system includes a vacuum detection component having a microcontroller operatively coupled to a pressure switch, a temperature sensor, and a shut off valve, which the microcontroller sends and receives, respectively, signals therefrom, a control valve located between the canister and the engine, and a processor communicating with the microcontroller. The vacuum detection unit is located on a conduit between an atmosphere and a canister, the canister communicates with an engine and the atmosphere, and the engine communicates with a fuel tank. The microcontroller processes the signals, determines a diagnostic result based on the signals, provides a communication interface, and sends the diagnostic result to the processor. The processor is operatively coupled to the control valve and provides a communication interface, detects an onboard diagnostic error, requests a diagnosis, deletes a diagnosis result, determines whether the engine is off, requests operation of the shut off valve, and provides purge status.